In short: Freshly expressed breast milk keeps for up to 4 hours at room temperature, up to 4 days in the fridge at 4 °C or below, and is best used within 6 months in a freezer at −18 °C. Never refreeze thawed milk or warm it in the microwave, and date every portion.
Author: Eva Birsa, mum and co-founder of Evitas · Updated: 28 September 2026
How long breast milk lasts: storage chart
These times apply to milk for a healthy, full-term baby stored at home. Where official sources differ, we give the most cautious value, with the longer limit some sources allow in brackets.
| Where | Temperature | How long | Source |
|---|---|---|---|
| Room temperature | up to 25 °C | up to 4 hours | CDC, ABM |
| Cool bag with ice packs | cold | up to 24 hours, then fridge or use | CDC, NHS |
| Fridge (at the back, not in the door) | 4 °C or below | up to 4 days (NHS allows up to 8 days at 4 °C or below; if unsure of the temperature, up to 3 days) | CDC, ABM, NHS |
| Ice compartment of a fridge | – | up to 2 weeks | NHS |
| Freezer | −18 °C or below | best within 6 months (up to 12 months acceptable per CDC and ABM) | NHS, CDC, ABM |
| Thawed in the fridge | 4 °C or below | as soon as possible, within 24 hours at most (NHS advises using straight away); do not refreeze | CDC, NHS |
| Warmed or thawed at room temperature | room | use within 1–2 hours | CDC, ABM |
| Leftovers after a feed | – | use within 1 hour, then discard | NHS (CDC: 2 hours) |
Stricter rules apply to premature babies and babies in hospital – follow the advice of your hospital or paediatrician. Your midwife, health visitor or a lactation consultant (IBCLC) can also help with expressing and storing milk.
What to store breast milk in
The CDC recommends bags made for storing breast milk or clean, food-grade glass or plastic containers with tight-fitting lids. Ordinary plastic bags and disposable bottle liners are not suitable.
- Canpol babies breast milk storage bags 150 ml – according to the manufacturer, pre-sterilised, with a stand-up base, double zip, measuring scale, spout for pouring into a bottle and 20 labels. Single use only.
- Canpol babies breast milk storage bottles 3 × 120 ml – suitable for the fridge and freezer, BPA-free.
- Canpol babies milk and food storage containers 4 × 180 ml – handy later for baby food too.
- Canpol babies breast milk collector – catches milk leaking from one breast while you feed on the other (up to 50 ml per shell); then pour it into a bottle or bag.
Find more in our Breastfeeding and Canpol babies collections.
How to label and freeze breast milk
- Label every portion with the date (and time) expressed and the amount. Use the oldest milk first.
- Store small portions – the CDC suggests 60–120 ml or the amount your baby takes at one feed, so less goes to waste.
- Leave space at the top (about 2.5 cm), as milk expands when it freezes.
- Avoid the door of the fridge or freezer, where the temperature fluctuates most – store milk at the back.
- Cool fresh milk first. According to the CDC you can combine milk expressed on the same day, but do not add warm fresh milk to milk that is already chilled or frozen.
How to thaw breast milk
- Ideally overnight in the fridge – according to the ABM, slow thawing causes the least fat loss.
- If you need it straight away, place the sealed bag or bottle in a bowl of warm water or hold it under warm (not hot) running water.
- Do not thaw milk in the microwave, on the hob or in boiling water.
- Never refreeze thawed milk.
- The fat separates during storage – gently swirl the milk before feeding.
How to warm breast milk (without a microwave)
Warm the milk to body temperature by placing the bottle in a jug of warm water or holding it under warm running water. Test a few drops on the inside of your wrist before feeding. The NHS and CDC advise against microwaves because they create hot spots that can burn your baby's mouth; the ABM adds that microwaving reduces the activity of protective factors in the milk.
According to the ABM, a waterless warmer is also acceptable. The LOVI AirWarm bottle warmer warms with hot air, gently shakes the milk for even heat distribution and has programmes for room-temperature or chilled liquids, according to the manufacturer. Use the keep-warm function for water – use warmed breast milk within 1–2 hours.
Transporting milk: to work, nursery or on the go
Chilled milk can be carried in a cool bag with ice packs for up to 24 hours (NHS, CDC). Put it straight into the fridge on arrival or use it. If your baby is in childcare, add their name to every portion.
Hygiene: breast pump, bottles and containers
Take apart and wash all pump parts that touch milk after every use. For babies under 2 months, premature babies and babies with weakened immune systems, the CDC advises sanitising them at least once a day (for example with steam). The LOVI electric steam steriliser and dryer holds up to 4 bottles and 10 small accessories per cycle, sterilises in 10 minutes and then dries them, according to the manufacturer.
Which pump to choose, how to find the right flange size and how often to express is covered in our guide How to choose a breast pump. Browse our breast pumps, and for bottles to feed expressed milk see LOVI Mammafeel bottle.
Frequently asked questions
Can I refreeze thawed breast milk?
No. The CDC and NHS agree: never refreeze thawed breast milk. If you thawed it in the fridge, use it as soon as possible and within 24 hours at most.
Can I warm breast milk in the microwave?
No. Microwaves heat unevenly and create hot spots that can burn your baby. Use a warm water bath or a bottle warmer.
How much milk should I put in one bag?
About 60–120 ml, or the amount your baby drinks at one feed. Smaller portions thaw faster and reduce waste.
Can I combine milk from different pumping sessions?
According to the CDC, yes – if it was expressed on the same day and you cooled the fresh milk first. Write the date of the first session on the label.
How long can my baby drink from the same bottle?
Once your baby has started drinking, the NHS advises using the rest within 1 hour and then throwing it away. Do not keep leftovers for the next feed.
Do these times apply to premature babies?
Not necessarily. These times are for healthy, full-term babies at home. For premature or unwell babies, follow your hospital's instructions.
Sources
- CDC – Breast Milk Storage and Preparation
- CDC – How to Keep Your Breast Pump Kit Clean
- NHS – Expressing and storing breast milk
- Academy of Breastfeeding Medicine – Clinical Protocol #8: Human Milk Storage Information for Home Use for Full-Term Infants (2017)
This content is for information only and does not replace advice from your paediatrician, midwife or lactation consultant.
